Increase in long-term energy system cost for the nuclear phase-out scenario compared to the scenario with continued dependence on nuclear power is limited (in average 0.13% of national GDP).

Phase-out of nuclear energy increases the importance of renewable energy and Carbon Capture and Storage (CCS) technology. These technologies and industries need to be developed as quickly as possible.

Additional supply of natural gas needs by up to about 50% to be secured as the demand increases considerably up to 2030.

Realising a low-carbon society while phasing out nuclear power may require more energy demand reduction than ever through changes in economic structure and lifestyle.

1. Background and objectives

Following the Fukushima nuclear disaster, Japan is going through a full revision of its energy and environment policy. However, most of the public debates focus on short-term energy supply and cost issues and not on the long-term implications taking into account Japan’s long-term commitment to climate change mitigation.

This research investigated the long-term economic implications of a gradual phase-out of nuclear power by 2050 on Japan’s energy system and on achieving long-term CO2 emissions reduction (-80% by 2050 compared to 1990 level). The research aims to highlight possible trajectories for the energy and environment policy of the country in the coming decades.

2. Research Scenarios

The following two scenarios were compared under the assumption that CO2 emissions will be reduced by 17% in 2020, 40% in 2030 and 80% in 2050 compared to 1990 levels (1.144 gigatonnes):

Reference (REF-LC) scenario
This scenario assumes the continued dependence on nuclear power in line with the 2010 Basic Energy Plan.

Electricity mix
Figure 1 presents the electricity mix for the two scenarios when the discounted total energy system cost is minimised. When nuclear power is not used, most of the fossil fuel-fired power plants are projected to be equipped with CO2 Capture and Storage (CCS) and renewable energy is introduced almost up to the limit defined on the basis of expert views. Moreover, natural gas-fired power increases by up to about 50% by around 2030, which indicates the importance of securing additional natural gas suppliers.

Figure 1: Electricity mix in 2030 and 2050

CO2 emissions
Figure 2 shows the breakdown of CO2 emissions for the two scenarios in 2050, together with the historic emissions data for 2005 as a reference. The results show that additional CCS requirements in 2050 in case of long-term nuclear phase-out will be about 170 MtCO2/yr in 2050.

Major dependence on a single low-carbon energy supply technology like CCS is not favourable. Major CO2 emissions reductions without relying on nuclear power will require not only the decarbonisation of energy supply but also tighter control over energy demand, for example, by more advanced changes in lifestyle and economic structure, without necessarily compromising the quality of life, through well-designed policy measures.

Figure 2: Breakdown of CO2 emissions in 2050. Model estimate for 2005 is also given for reference.

Energy Imports and Energy System Cost
The increase in discounted total energy system costs for 2010-2050 for the NPO-LC scenario compared to the REF-LC scenario was found to be 1%. In annual terms, the average energy system cost increase was found
to be about 0.13% of national GDP. Most of this cost increase is attributable to an increase in fossil fuel imports